Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)
O 35.125: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster B
An oxygen annealing chamber for the preparation of clean hard metal substrates — •Johannes Friedlein, Andreas Sonntag, Benjamin Ehlers, Stefan Krause, and Roland Wiesendanger — University of Hamburg, Institute of Applied Physics, Jungiusstr. 11A, 20355 Hamburg, Germany
Reproducible measurements on the atomic scale require surfaces of high purity. The preparation of hard metal substrates like W and Mo crystals for scanning tunneling microscopy experiments involves creating a surface impurity depletion zone by annealing in oxygen atmosphere (p ≤ 1 × 10−6 mbar) at high temperature (T ≤ 2000 ∘C) [1-2].
We present the design and construction of a dedicated preparation chamber for clean W and Mo surfaces. It has a separate pumping system, consisting of turbo, ion getter and titanium sublimation pump. An ion gauge and a mass spectrometer allow for the control and analysis of vacuum conditions. The preparation process is conducted via remotely controlled O2 leak valve and electron beam heating. During the annealing process the surroundings heat up leading to an increase of their degasing rates. To avoid this we implement a water cooling system for the chamber wall as well as for the heating stage.
[1] M. Bode, S. Krause, L. Berbil-Bautista, S. Heinze, R. Wiesendanger, Surface Science 601, 3308 (2007).
[2] Kh. Zakeria, T.R.F. Peixotoa, Y. Zhanga, J. Prokopa, J. Kirschner, Surface Science 604, L1 (2010).